But you could set the permissions and ownership for all files and directories to only your account. Here's a link about -> http://support.microsoft.com/kb/224623 After that be sure to remove the other's rights.
-> Just for closure the only other fix (hardware) is to take it with you. I never suggest drive or file lock software since I have too many people who have lost it all with those.
I have other people logging in to my computer. I have an external hard drive that is attached for Back ups and other tasks that I want to secure. Now anyone can access it, even though I am the administrator and have Password status. I have searched all the files and helps to no avail. How do I do that? Thanks!!